MetaBoxes: Saving meta boxes don't reset the comment/ping status

[youknowriad]

closes #4843 and closes #4663

This PR fixes two related issues:

• The meta boxes save was being triggered even if we didn't have any meta box enabled
• The meta boxes save was resetting the ping/comments status due to legacy code on the backend. I ensured the post status and ping status are passed to the meta box request to avoid this.

Testing instructions

• Add some metaboxes
• Save your post
• Refresh the page
• The ping and comment status should stay enabled unless you disable them explicitely.

[youknowriad]

⌛️ I don't blame you 🙂 no one wants to review meta boxes.

[gziolo]

You can express it also as:

const additionalData = [
    post[ 'comment_status' ] && `comment_status=${ post[ 'comment_status' ] }`,
    post[ 'ping_status' ] && `ping_status=${ post[ 'ping_status' ] }`,
].filter( Boolean );

I learned this trick with filter recently :)

[gziolo]

Code looks good. I haven't tested yet.

[aduth]

Does post need to come through the action, or could we assume that the value in store.getState() would be up to date by now?

[youknowriad]

Yes, it's probably the same, I'll remove the post from the action

[gziolo]

Is it? I mean, it might be the same. It all depends how all those dispatch actions are processed. This is quite tricky because you dispatch action in the middle of another dispatch. At the moment when you trigger requestMetaBoxUpdates action, the payload of requestPostUpdateSuccess is still processed, so there might be a different value in the store at that time. I think actions are dispatched asynchronously which means it should all end up as expected.

[aduth]

Typo: "addition" -> "additional"

[aduth]

Aside: Would it be easier to construct this with FormData instead?

Unfortunately not possible to pass an object to its constructor, needs to iterate with FormData#append.†

But it can be passed directly into fetch's body property.

Above jQuery.serialize would need to be revised to jQuery.serializeArray.

I think FormData manages encoding too, unlike the current code here where we concatenate post[ 'comment_status' ] into the form without first encodeURIComponent (not likely a real-world issue).

† There are helpers like object-to-formdata

[gziolo]

I’m afraid FormData doesn’t work properly with our codebase. We polyfill fetch with very limited support for FormData. At least I had a few issues with it a few weeks back. I don’t remember the details though 😃

[gziolo]

Please note the gaps for Edge and Safari: https://developer.mozilla.org/en-US/docs/Web/API/FormData.

[youknowriad]

I tried something similar the problem is that serializeArray doesn't return a nested array when we have array parameters instead it returns something like { "fields[foo]": "bar" } which is not the correct object we want.

[aduth]

Unnecessary square brackets here on property access. Surprised this isn't a lint error.

[youknowriad]

I'm merging this one as it's a necessary fix for the release.